Power fuel supply system for an internal combustion engine carburetor

ABSTRACT

A power fuel supply system for a multi-barrel carburetor of an internal combustion engine. The system includes a power valve which in its preferred embodiment has a two-stage operation. The first stage opens in response to a drop in manifold vacuum while the second stage is mechanically actuated near a wide-open throttle position by a linkage connected to the throttle lever. The power valve includes a sleeve or piston which when the valve is closed prevents communication between the left-hand and righthand fuel supply passages of the carburetor and thereby prevents undesirable interaction effects to the separate fuel metering signals.

United States Patent 1191 Herbert et al.

1451 Sept. 23, 1975 1 POWER FUEL SUPPLY SYSTEM FOR AN INTERNALCOMBUSTION ENGINE CARBURETOR [75] Inventors: Clarence C. Herbert,Southgate;

Thomas R. Johnson, Ann Arbor; Anthony Verduce, Plymouth, all of Mich.

[73] Assignee: Ford Motor Company, Dearborn,

Mich.

[22] Filed: Jan. 7, 1974 [21] Appl. No.: 431,454

52 U.S. c1 261/23 A; 261/51; 261/69 R; 137/625; 137/68 51 1111.01! F02M7/22 [58] Field of Search 261/69 R, 69 A; l37/625.68, 613; 261/51, 23 A[56 References Cited UNITED STATES PATENTS 2,010,329 8/1935 Speth137/625.68 2,406,114 8/1946 Sloane et al. 261/69 R 2,634,751 4/1953Borer l37/625.68 5/1961 Wildem 137/613 Primary Examiner-Tim R. MilesAttorney, Agent, or Firm-Roger E. Erickson; Keith L. Zerschling [57]ABSTRACT A power fuel supply system for a multi-barrel carburetor of aninternal combustion engine. The system includes a power valve which inits preferred embodiment has a two-stage operation. The first stageopens in response to a drop in manifold vacuum while the second stage ismechanically actuated near a wideopen throttle position by a linkageconnected to the throttle lever. The power valve includes a sleeve orpiston which when the valve is closed prevents communication between theleft-hand and right-hand fuel supply passages of the carburetor andthereby prevents undesirable interaction effects to the separate fuelmetering signals.

6 Claims, 5 Drawing Figures US Patent Sept. 23,1975 Sheet 1 of33,907,941

US Patent Sept. 23,1975 Sheet 2 of 3 3,907,941

-Inl-ll JIHI IHH III I LL F'IG.3

US Patent Se'pt; 23,1975 Sheet 3 of 3 3,907,941

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POWER FUEL SUPPLY SYSTEM FOR AN INTERNAL COMBUSTION ENGINE CARBURETORBACKGROUND AND SUMMARY OF THE INVENTION Many carburetors used inautomobile engines today employ a power fuel supply system to supplementthe main fuel supply system during acceleration or heavy loading of theengine. Such a power fuel supply system generally includes a valve whichresponds to a drop in intake manifold vacuum to provide a richer mixtureto the engine combustion chamber in accordance with the demand for morepower.

One type of power fuel supply system used extensively in presentlyproduced carburetors employs a simple on-off valve that opens when theintake manifold vacuum drops below a certain magnitude to provideadditional fuel to the engine. These valves can be constructed fortwo-stage operationby providing valve elements that open successively.Another type of power fuel supply system utilizes a comparativelyexpensive metering rod cooperating with a metering orifice or jet toprovide a continuously variable power fuel flow more closelycorresponding to the magnitude of the vacuum drop within the intakemanifold.

Particular problems may occur with carburetors having two or morebarrels in which one of the barrels feeds one group of engine cylindersand the other of the barrels feeds another group of engine cylinders.For reasons of economy and packaging, it is common for each of theinlets to the fuel supply system for the two or more barrels to beregulated by a single vacuum responsive power valve. The valve when openpermits fuel to enter a chamber where the inlets to the fuel deliverypassages are located. US. Pat. No. 3,172,923 granted to Romeo et al. onMar. 9, 1965 illustrates such a power fuel supply system. When the valveis closed it prevents fuel in the fuel bowl from entering the chamber,but it does not seal one inlet from the other. Consequently, fuel signalinteraction occurs through the chamber from one fuel delivery passage tothe other which may adversely affect the fuel metering signals of therespective barrels. Because the power fuel supply systems of manypresent day carburetors feed directly into or are combined with the mainfuel metering systems, fuel signal interaction between delivery passagesin the power fuel supply system also provides interaction between theseparate sides of the main fuel system.

It is an object of this invention to provide a power fuel supply systemfor a multi-barrel carburetor which when the power valve is closedisolates the right-hand fuel supply passages from the left-hand fuelsupply passages, thereby preventing fuel signal interaction. It is afurther object of the invention to provide a two-stage power fuel supplysystem in which one of the stages is actuated in response to intakemanifold vacuum and the second stage is actuated mechanically. Finally,it is an object of the invention to provide a power fuel supply systemthat is economical to produce and integrate with existing carburetorstructures.

A power fuel supply system constructed in accordance with this inventionincludes a carburetor fuel bowl and a power valve assembly receivingfuel from the fuel bowl. A pair of fuel passages receive fuel from thepower valve assembly and conduct the fuel to a pair of carburetorbarrels or venturis. The power valve assembly includes a vacuum motorincluding a movable element displaceable in response to changes inintake manifold vacuum. A sleeve or piston is slidingly received withina bore of the valve assembly. A passage is formed within the piston andhas an inlet opening on the sliding surface of the piston and an outletopening to the pair of fuel passages. The piston isdisplaceable to oneextreme position in which the portion of the piston which contains theinlet is uncovered and protrudes outwardly from the bore while theoutlet is simultaneously in communication with the fuel passages. Whenthe piston is in this position, the fuel bowl is connected to the fuelpassages. The piston is displaceable to an opposite extreme position inwhich the outlet is closed to the pair of fuel passages andcommunication between the fuel bowl and the fuel passages and betweenthe first and second fuel passages is prevented;

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view of acarburetor incorporating the invention.

FIG. 2 is a top view of a portion of the carburetor assemblyincorporating the invention.

FIG. 3 is a cross sectional view taken along line 33 of FIG. 2.

FIG. 4 is a cross sectional view taken along line 4-4 of FIG. 3.

FIG. 5 is a top view taken along line 55 of FIG. 4.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT Reference numeral 11refers generally to a twobarrel carburetor having a pair of barrels orinduction passages 13 and 15. The first induction passage 13 haspositioned within it a fuel inlet venturi assembly 17 connected to amain fuel well 19 which, in turn, is connected to the fuel bowl 21 bymeans of a fuel passage 23 and a metering jet 25. Similarly, the secondinduction passage 15 has positioned within it a second inlet venturiassembly 27 connected to a second main well 29 which, in turn, is joinedto the fuel bowl 21 by means of fuel passage 31 and the second mainmetering jet 33. Pivotally mounted within the fuel bowl is a float andvalve assembly 35 which regulates the fuel level within the fuel bowl.

A throttle lever assembly 37 includes a lever element 39 fixed tothethrottle shaft (not shown). A second lever element 41 is pivotallymounted to the throttle shaft and abuts the first element 39 during thelater portion of throttle opening movement. Spring 43 biases theadjustment screw 44 of lever element 41 against tab 46 of lever 39during the latter portion of throttle open ing movement so that the twolevers then move simultaneously. A third element 45 of the assembly 37is resiliently connected to lever element 39 and moves simultaneouslywith lever element 39 during the first portion of its opening travel todisplace link 50 and actuate accelerator pump 47. The lever element 41is pin-joined to an adjustable link 49 connecting a lever with L- shapedshaft member 51 pivotally mounted within the carburetor cover 53. Thehorizontal portion of member 51 has a semi-cylindrical portion removedproviding a flat side 55 that acts as a cam against the upper surface 57of the lever 59. Lever 59 is pivotally attached within the fuel bowl 21to die main body of the carburetor and pivots about shaft 61 in responseto rotation and the cam action of member 51. The lower end 63 of lever59 rests on top of element 65 of the power valve assembly, as shown inFIG. 3 of the drawings.

The power valve assembly 67 (shown in detail by FIG. 4) has a main body69 including a cylindrical portion 71 received within a bore 73 formedin the carburetor body. The upper end of the cylindrical portionprotrudes into the fuel bowl 21. A flanged portion 75 of the power valvebody 69 has an upper surface abutting a mounting pad 77 formed on theunderside of the carburetor body. A gasket 79 separates the uppersurface and the pad. A flexible diaphragm 80 is held between the lowersurface 81 of the flanged portion and a cover 83. The cover and thepower valve main body 69 are mounted to the carburetor main body bysuitable threaded fasteners (not shown). The volume immediately beneaththe diaphragm 80 connected to a source of intake manifold vacuum bymeans of passage 82. The volume immediately above the diaphragm is atatmospheric pressure, similar to the fuel bowl 21. The central portionof the diaphragm 80 is sandwiched between a disc 84 and a cup 85. Anupwardly extending pintle 87 is rigidly attached to the disc 84 and cup85 and is biased upwardly by compression spring 88 into a bore 89 formedin the valve body adjacent the junction of the cylindrical portion 71and the flanged por tion 75. Positioned over and about the upwardlyextending pintle is a hollow cylindrical sleeve or piston 91 having aclosed upper end 92 and an open lower end 90. The sleeve is movablewithin bore 89 and is biased downwardly against the top of the pintle bya compression spring 93. The spring acts against restriction element 94positioned within an orifice 95 at the upper end of the cylindricalportion 71 of the valve body. The sleeve includes inlets 96 whichconnect the interior or chamber 97 of the cylindrical portion of thevalve body through the hollow interior of the sleeve 91 with a pair ofrestricted passages 98 and 99 when the sleeve in its uppermost positionas shown in FIG. 4 of the drawings.

The restriction element 65 includes a metering orifice 101 thatcommunicates the interior 21 of the fuel bowl with the interior 97 ofthe cylindrical portion of the valve body at all times. The restrictionelement is displaceable downwardly by the force of the lever 59 to causethe restriction element seal 102 to unseat from against the orifice 101and to create a substantially greater communication and flow between thefuel bowl to the interior 79 of the cylindrical portion of the valvebody. A horizontally extending slot 103 is formed in the upper tip ofthe restriction element 65 to prevent the lower surface 63 of the lever59 from obstructing the metering orifice 101.

Passages 98 and 99 are connected to the fuel passages 23 and 31,respectively, by means of grooves 105 and 107 and risers 109 and l 1 1,respectively. Openings 113 formed in the gasket 79 permit the grooves105 and 107 to discharge into risers 109 and 111, respectively.

OPERATION The power fuel supply system described above provides anincreased flow of fuel to the carburetor induc tion passages underconditions of heavy loading or acceleration. The lower chamber of thevacuum motor beneath disphragm 80 is in communication with the source ofintake manifold vacuum. The volume above the diaphragm 80 is incommunication with the fuel bowl 21 and is at atmospheric pressure.Under idle conditions or small throttle openings, the intake manifoldvacuum is high and the diaphragm and pintle 87 are drawn downwardlyuntil the bottom rim of the cup engages or nearly engages the cover 83.With the pintle in its lowermost position, the compression spring 93biases the sleeve 91 downwardly so that the bottom rim. of the sleeve 91drops below the openings to passages 98 and 99 and flow from the fuelbowl to the passages and communication between the passages, isprecluded.

Upon engine acceleration or heavy loading, the vacuum within the intakemanifold of the engine drops significantly thereby reducing the pressuredifferential experienced by the diaphragm so that the spring 88 urgesthe diaphragm and pintle 87 upwardly to the position as shown in FIG. 4.The pintle carries the sleeve upwardly against the bias of the spring 93to the position as shown in FIG. 4 in which the openings to passages 98and 99 are open and in communication through the interior of sleeve 91with the fuel bowl 21. Fuel is then drawn through passages 98 and 99 andintroduced into the respective induction passages. The quantity of fuelis metered by orifice 101.

When the throttle lever 39 is about two-thirds open it engagesadjustment screw 44 of lever 41. Further, opening travel of lever 39displaces lever 41 resulting in corresponding displacement of member 51.The flat 55 on member 51 cams lever 59 which pivots about shaft 61. Thelower portion 63 of lever 59 engages element 65 and displaces itdownwardly opening the larger orifice and permitting relativelyunrestricted flow of fuel into the chamber 97. Fuel flow throughpassages 98 and 99 is then metered by restrictions positioned withinthose passages.

It may be seen that the above-described invention provides a two-stagepower fuel supply system; the first stage actuated by intake manifoldvacuum and the second stage actuated by mechanical linkage from thethrottle lever assembly. It also may be seen that when the intakemanifold vacuum is high and the power valve is closed, the right-handpassage 99 is completely closed from the left-hand passage 98 by theinterposition of the sleeve 91 in its lowered position, therebypreventing mixture of the fuel metering signals and interaction betweenthe fuel passages.

Modifications and alterations will occur to those skilled in the artwhich are included within the scope of the following claims:

We claim:

1. A power fuel supply system for an internal combustion enginecarburetor having at least two barrels and throttle valves pivotallymounted within said barrels,

said carburetor including a fuel bowl, a power valve receiving fuel fromsaid fuel bowl, and first and second fuel passages receiving fuel fromsaid power valve and discharging it into first and second of saidbarrels, respectively,

said power valve including a housing having a vacuum motor at one endthereof,

said vacuum motor having a variable volume chamber in communication witha source of engine intake manifold vacuum, said vacuum motor including amovable element displaceable in response to intake manifold vacuumpressure,

said power valve including a bore and a piston means slidingly receivedwithin said bore in engagement with said movable element,

said piston means having an inlet and an outlet openable to said firstand second fuel passages,

said piston means being resiliently held in a first postion in which itblocks the outlet from the first and second fuel passages and the firstfuel passage from the second fuel passage,

said piston means being movable by the vacuum motor to a second positionin which the outlet is in communication with the first and second fuelpassages,

a flow restrictor resiliently mounted within an opening in said housingand having an orifice to permit fuel flow from said fuel bowl to saidpiston means inlet,

a throttle lever pivotally movable with said throttle valves,

and motion transfer means interconnecting said restrictor and thethrottle lever to displace said restrictor when the throttle leverreaches a predetermined position, said restrictor when displacedpermitting increased fuel flow into said housing through said opening.

2. A power fuel supply system according to claim 1,

said restrictor being displaced to open the opening in said housingduring the latter portion of throttle lever opening movement.

3. A power fuel supply system according to claim 1,

said movable element comprising a pintle,

said piston comprising a cylindrical sleeve having abutment meansadjacent one end thereof, said pintle extending into said piston andbeing engageable with said abutment means.

4. A power fuel supply system according to claim 1, a first compressionspring biasing said movable element and said piston toward said firstposition,

a second compression spring acting between said piston and saidrestrictor, said second spring opposing said first spring, said secondspring biasing said restrictor toward said opening, said first springhaving greater stiffness than said second spring.

5. A power fuel supply system according to claim 1,

the portion of said power valve housing including said opening and saidrestrictor within said opening protruding into said fuel bowl.

6. A power fuel supply system according to claim 1,

said motion transfer means including a cam member and a second lever,the second lever extending between the cam member and the restrictor,

opening movement of said throttle lever past said predetermined positioncausing rotation of said cam member and opening of said restrictor.

1. A POWER FUEL SUPPLY SYSTEM FOR AN INTERNAL COMBUSTION ENGINE CARBUETOR HAVING AT LEAST TWO BARRELS AND THROTTLE VALVES PIVOTALLY MOUNTED WITHIN SAID BARRELS, SAID CARBURETOR INCLUDING A FUEL BOWL, A POWER VALVE RECEIVING FUEL FROM SAID FUEL BOWL, AND FIRST AND SECOND FUEL PASSAGES RECEVING FUEL FROM SAID POWER VAVE AND DISCHARGING IT INTO FIRST AND SECOND OF SAID BARRELS, RESPECTIVELY, SAID POWER VALVE INCLUDING A HOUSING HAVING A VACUUM MOTOR AT ONE END THEREOF, SAID VACUUM MOTOR HAVING A VARIABLE VOLUME CHAMBER IN COMMUNICATION WITH A SOURCE OF ENGINE INTAKE MANIFOLD VACUUM, SAID VACUUM MOTOR INCLUDING A MOVABLE ELEMENT DISPLACEABLE IN RESPONSE TO INTAKE MANIFOLD VACUUM PRESSURE, SAID POWER VALVE INCLUDING A BORE AND A PISTON MEANS SLIDINGLY RECEIVED WITHIN SAID BORE IN ENGAGEMENT WITH SAID MOVABLE ELEMENT, SAID PISTON MEANS HAVING AN INLET AND AN OUTLET OPENABLE TO SAID FIRST AND SECOND FUEL PASSAGES, SAID PISTON MEANS BEING RESILIENTLY HELD IN A FIRST POSTION IN WHICH IT BLOCKS THE OUTLET FROM THE FIRST AND SECOND FUEL PASSAGE, AND THE FIRST FUEL PASSAGE FROM THE SECOND FUEL PASSAGE, SAID PISTON MEANS BEING MOVABLE BY THE VACUUM MOTOR TO A SECOND POSITION IN WHICH THE OUTLET IS IN COMMUNICATION WITH THE FIRST AND SECOND FUEL PASSAGES, A FLOW RESTRICTOR RESILIENTLY MOUNTED WITHIN AN OPENING IN SAID HOUSING AND HAVING AN ORIFICE TO PERMIT FUEL FLOW FROM SAID FUEL BOWL TO SAID PISTON MEANS INLET, A THROTTLE LEVER PIVOTALLY MOVABLE WITH SAID THROTTLE VALVES, AND MOTION TRANSFER MEANS INTERCONNECTING SAID RESTRICTOR AND THE THROTTLE LEVER TO DISPLACE SAID RESTRICTOR WHEN THE THROTTLE LEVER REACHES A PREDETERMINED POSITION, SAID RESTRICTOR WHEN DISPLACED PERMITTING INCREASED FUEL FLOW INTO SAID HOUSING THROUGH SAID OPENING.
 2. A power fuel supply system according to claim 1, said restrictor being displaced to open the opening in said housing during the latter portion of throttle lever opening movement.
 3. A power fuel supply system according to claim 1, said movable element comprising a pintle, said piston comprising a cylindrical sleeve having abutment means adjacent one end thereof, said pintle extending into said piston and being engageable with said abutment means.
 4. A power fuel supply system according to claim 1, a first compression spring biasing said movable element and said piston toward said first position, a second compression spring acting between said piston and said restrictor, said second spring opposing said first spring, said second spring biasing said restrictor toward said opening, said first spring having greater stiffness than said second spring.
 5. A power fuel supply system according to claim 1, the portion of said power valve housing including said opening and said restrictor within said opening protruding into said fuel bowl.
 6. A power fuel supply system according to claim 1, said motion transfer means including a cam member and a second lever, the second lever extending between the cam member and the restrictor, opening movement of said throttle lever past said predetermined position causing rotation of said cam member and opening of said restrictor. 